Chevy & GMC Vans

have intermittant rear brake noise...the only way I know to describe it is is sounds like metallic "squirrelsquirrelsquirrel"
ok, that has target writen all over it, go ahead make your jokes about my 4.3....
anyway,
pulled the drums and inspected.
the cylinders in the drum brakes are fairly new, no leaks, boots look good, the shoes have +/- 1/4" of friction material on them. I've bled the lines till the fluid is clear. The shoes are totally budget, cheapest of the cheap. Drum wear is minimal, no ridge on the outboard edge of the drum, inside face is pretty smooth. Braking action is fine.
on a medium to hard brake, or a soft brake at speed no noise. easing up to a red light is when I get this disconcerting noise.
Due to drone from the muffler, I can't tell if I'm getting any noise from the axle bearings at highway speeds. Do you think this might be bad bearings? I can't visually see anything wrong with the brakes.
Need some ideas.

thanks for the confirmation. I've come to the same conclusion. I removed the drums and did some cleaning, lubricating and adjustment and got rid of the noise. Although the self adjustment components are the same as any other drum brake system I've ever seen, mine seem to collect brake dust and stop self adjusting in pretty short order. I think your right about the brake linings, next time I need to buy much higher quality brake shoes.